1. Field of the Invention
This invention relates to an oil feeding device for feeding oil to an oil requiring portion.
The disclosure of Japanese Patent Application No. 2003-3 56811 filed on Oct. 16, 2003 including specification, drawings and claims is incorporated herein by reference in its entirety.
2. Description of Related Art
In a power transmission system mounted on a moving object, heat is generated on rotary elements forming a part of the power transmission system, and those rotary elements are worn away. In the prior art, therefore, oil is fed to cool and lubricate where the heat is generated or where to be worn. There are known two kinds of method for feeding oil to the heating portion or wearing portion of the power transmission system. The first oil feeding method is a so-called scraping method, in which oil is fed to the oil requiring portion by scraping up the oil in an oil reservoir by the rotary elements constituting a part of the power transmission system. The second oil feeding method is a so-called compulsory lubricating method, in which oil is fed to the oil requiring portion by suctioning the oil in the oil reservoir by an oil pump.
As compared to the second oil feeding method, the first oil feeding method has the advantage to realize weight and cost savings because oil pump is not required therefor. One example of the first oil feeding method is disclosed in Japanese Utility Model Laid-Open No. 63-166608. In this Japanese Utility Model Laid-Open No. 63-166608, there is disclosed a lubricating device for an engine to be employed in a so-called moving object such as a motorcycle, a three-wheeled vehicle and so on. Specifically, there are provided a crankshaft, and a drive shaft and a power taking-off shaft of a transmission in a crankcase, and a clutch is installed on one of the end portions of the drive shaft. Also, a plurality of speed change driving gears is provided on the drive shaft. On the other hand, a plurality of speed change driven gears is provided on the power taking-off shaft, and a plurality of the speed change driving gears and a plurality of the speed change driven gears are meshed with each other.
Moreover, an oil passage is formed on an inner wall of the crankcase, which is communicated with an oil chamber. The oil chamber is arranged in an upper space of the crankcase, and an oil dropping hole is provided in the oil chamber. This oil dropping hole is arranged directly above the portion where a plurality of speed change driving gears and a plurality of speed change driven gears are meshed with each other. According to the above-mentioned construction, the oil collecting on a bottom portion of the crankcase is scraped up by a rotation of the clutch, and the scraped oil is fed to the oil chamber through the oil passage. The oil fed to the oil chamber drops out of the oil dropping hole to lubricate and cool the portion where a plurality of speed change driving gears and a plurality of speed change driven gears are meshed with each other.
According to the lubricating device for the engine disclosed in the aforementioned Japanese Utility Model Laid-Open No. 63-166608, however, when the moving object is accelerated or decelerated, a force acts relatively on the oil dropping from the oil dropping hole of the oil camber in an accelerating or decelerating direction of the moving object. As a result of this, the oil drops on the portion out of the meshing portion of the gears, so that an amount of the oil fed to the meshing portion of the gears decreases. Therefore, the oil runs short at the meshing portion of the gears, and this may degrade a lubricating performance and a cooling performance.